The death of Lazcano represents a significant blow for the Zetas, a group considered to be the most powerful and ruthless of Mexico's drug cartels.

According to the Navy, an exchange of fire took place on Sunday afternoon in the municipality of Progreso, as Mexican Marines patrolled the area. The Marines were attacked with grenades but managed to kill two criminals, including Lazcano, the leader of the Zetas organization.

The Navy initially reported that it had killed a man believed to be Lazcano on Monday night, but at that stage it said it was still waiting for forensic evidence to confirm this.

On Tuesday morning the Navy issued a second statement, which said that fingerprints taken from one of the corpses in its possession coincided with those of the Zetas leader.

Lazcano enlisted in the Mexican army at age 17 and was eventually appointed to a Special Forces counter-narcotics unit in the north of Mexico. But in 1998 he became one of the founding members of Los Zetas, a group of 30 soldiers who abandoned the Mexican army to work as enforcers for the Gulf Cartel.

The Zetas eventually split from the Gulf Cartel and became their own drug trafficking group. Lazcano became the Zetas commander in 2004 after the capture of Zetas leader Rogelio Gonzalez. He is suspected of having ordered hundreds of killings, and Mexican officials believe he planned the murder of investigative journalist Francisco Ortiz Franco, who was killed in Tijuana in 2004.

Mexican police believe that the Zetas organization has recently been plagued by an internal power struggle that has led to increased violence in northeastern Mexico, where the Zetas are also fighting their former allies, the Gulf Cartel.

The Zetas are accused of several mass killings, such as the assassination of 72 migrants in San Fernando, Tamaulipas state, in 2010.

The Zetas are also accused of smuggling people into the U.S. and of forcibly recruiting migrants to work in their ranks. They are known to use ruthless tactics in their war against other cartels and the Mexican state, like beheading enemies and skinning people alive.

On Monday, the Mexican government also announced it had captured regional Zetas leader Salvador Alfonso Martinez who is accused of ordering the massacre of migrants in San Fernando.

Another Zetas leader known as "El Talibán," was arrested in September. "El Talibán," whose real name is Iván Velázquez Caballero, had deserted the Zetas and gone back to the Gulf Cartel.